<i>At the beginning of the empire, the tax rates were low and the revenues were high. At the end of the empire, the tax rates were high and the revenues were low.</i>
-Ibn Khaldun

Ibn Khaldun is one of the greatest scholars that have given significant contribution. His ideas encompasses the time dimension and still relevant with our present condition. He has great contributions on various economic issues, such as concepts of agriculture, demand and supply, and price interdependence as written in his Muqaddimah. Ibn Khaldun is the first thinker to systematically analyze the functioning of an economy, the importance of technology, specialization and foreign trade in economic surplus, and the role of government and its stabilization policies to increase output and employment. Moreover Ibn Khaldun dealt with the problem of optimum taxation, minimum government services, incentives, institutional framework for an economy, law and order, expectations, production, and the theory of value. Ibn Khaldun is the first economist, using the language of economic surplus, who has conducted a biological interpretation of the rise and fall of nations.

<b>Economic Theory of Ibn Khaldun and Rise and Fall of Nations</b>
http//www.bilgesam.com/en/index.php?option=com_content&view=article&id=182economic-theory-of-ibn-khaldun-and-rise-and-fall-of-nations&catid=116analizler-ekonomi&Itemid=142

<b>Ibn Khaldun's Theory of Taxation and its relevance today</b>
http//www.scribd.com/doc/12664863/Ibn-Khalduns-Theory-of-Taxation-and-Its-Relevance-Today

<b>Ibn Khalduns Contribution on Modern Economics Development
An Analysis based on Selected Economic Issues</b>
http//www.uned.es/congreso-ibn-khaldun/pdf/06%20Irfan%20Beik.pdf

Islamic scholars has worked regarding economics issues. Hazrat Imam Abbu Yusuf who was the most honourable student of Imam Abbu Hanifa (R.A) wrote a famou book on various ecnomic entitled "Kitab al Kharaj". It is also considered as first book of world on taxation. In his he dealt with taxation in Islamic state and cannons of taxation.

In wikipedia the following remarks about Kitab al Kharaj are mentioned

<b>Kitab al-Kharaj, his most famous work, is a treatise on taxation and fiscal problems of the state prepared for the caliph</b>
Regards,